With continued miniaturization of electronic components the range of portable devices continues to grow yearly. Media players for music and video are becoming common place, measurement devices such as laser measurement tools are becoming less expensive and common enough to find in retails stores, and devices that previously had been embodied in low technology, such as flashlights, are becoming highly complex devices with computer chips controlling bright white LED lamps allowing selection of brightness and higher power efficiency. This wide range of devices have widely differing power requirements and this has yielded a wide array of batteries to meet the needs of these portable devices.
One major difficulty with the advent of so many portable devices is the need to maintain their batteries. In many cases the batteries are simply removed and replaced with new batteries and the old ones discarded. This can be wasteful of resources as more devices require batteries and more batteries are disposed. Rechargeable batteries reduce the waste but require special battery chargers as the differing chemistries and sizes for the various kinds of batteries require different methods and connection methods for recharge. Therefore users with many portable devices often need several chargers; perhaps one for a mobile phone, another for a PDA (Portable Digital Assistant), another for a digital camera and yet another for a portable music or video player. Otherwise the user must carry replacement batteries for each portable device. Typically each of these devices uses a different battery due to their differing size and power requirements.
There are three well known methods of connecting to a battery under use or recharge. The first common method is by way of a metal tab or leaf spring. These can be seen in common portable devices where a bent metal tab presses against the battery when it is placed into its compartment. A second method, which is similar in application to the leaf spring contact, is the spiral spring contact. Again these are common in electronic devices where a battery is placed into a physical compartment and one or both ends are pressed against a spring for its electrical and physical contact to the rest of the circuit. In many cases a leaf spring and a spiral spring are used together. The leaf contacts the positive bump at one end of a standard battery and the spiral spring contacts the flat negative end at the other. This combination offers a certain amount of polarity protection helping to prevent the user from putting the battery in backwards and possibly damaging the device. In both of these previously noted cases the batteries are often not charged within the device. This is especially true when the batteries are of a standard size, such as A, AA, C or D since several chemistries exist for the same size of battery each requiring a different method of monitoring charge completion. Using the wrong method to charge a battery can cause damage to the battery which in turn can damage the device itself, possibly through leakage or even combustion of the battery.
The third common method applied is a contact pad and bent pin. This method is very common in mobile phones and devices where the battery is seldom if ever removed. When this method is employed the battery typically has a gold plated contact pad and the device typically has a gold plated bent pin contact. The battery is typically held against its contact by some form of spring latch or battery cover panel. In these cases the battery is of a known type, with its chemistry and charging needs known by the manufacturer and therefore its charging needs can be met quite easily by a dedicated internal or external charging circuit. For rechargeable devices that are intended to be used and charged repeatedly, this pin and pad method of connection is most common and a dedicated battery type is almost always used. In all of the above cases the compartment is sized for a specific battery type.
In some so called “universal battery chargers” a chamber that is long enough to accept the largest target battery is used and a spring loaded contact holds the smallest target battery in place but can be levered into place to receive the largest acceptable battery size.
In some few cases the battery may have a metal plate or magnet affixed to it so that it can be held into place with a magnet. This method is common in rechargeable phones where the phone and or cradle has a magnet and the phone, when rested in the cradle, comes into contact with charging pads that can then recharge the handset.
In all of the above stated examples the power is supplied from an external adapter that is plugged into an AC wall outlet. The supply is normally a DC power adapter for portable electronic devices, commonly called a “wall wart”. The voltage supplied by the power adapter is fixed such that it meets the device's needs precisely for charging the battery. Internal circuitry, such as a buck or boost converter may be employed if the input voltage needs to be converted to a different value to match the needs of charging the battery.
Some designs employ magnets to improve electrical connectors, but rarely does the magnet itself make the electrical contact. For instance relays employ a magnet or electromagnetic device to pull a movable spring contact onto a fixed contact to close a circuit. Other similar devices move a rocker contact into position, telephone cross-bar switches once worked in this way. Examples of magnetically movable contacts in the prior art are U.S. Pat. Nos. 5,931,683 and 3,750,083 as well as British patent GB2414603.
Another common example of magnets employed for making electrical connections involves building a magnet into one or both sides of a connector pair, such that the connectors are attracted and make a stronger or better aligned connection. Examples of this include U.S. Pat. Nos. 3,786,391, 3,810,258, 4,917,612, 5,779,487, 6,030,229, 6,231,349, 6,528,746, and 6,875,035; Japanese patent applications JP2002-237354, JP2003-036933, JP2003-249317; and Japanese patent JP11027868.
A few items in the prior art connect to batteries, but are special quick disconnect devices, also in two parts requiring one half of the pair to be affixed to the battery, typically a vehicle battery, and the other end is attached to a cable end. Examples of this include U.S. Pat. Nos. 4,609,238 and 4,390,232.
Another example of magnets used to make quick disconnect possible include the U.S. patent for connecting a safety grounding strap, U.S. Pat. No. 5,004,425, “Magnetic Snap Assembly for Connecting Grounding Cord to Electrically Conductive Body Band” and the international patent application WO2004-095647A1 “Safety Wire Connector” which shows how to connect two wires together that can be quickly disconnected.
One category of methods for using magnets is to make electrical test connectors for examining circuits and electronic devices. British patent GB1181111, which corresponds with U.S. Pat. No. 3,512,116 shows a method of attaching leads via magnets to female connections on circuit boards. International patent WO0150140 “Test connector” offers “improved connectivity due to magnetization of tip” and U.S. Pat. No. 4,377,003 “Testing Device for Electronic Circuits” which is intended “Especially for Portable Radios” shows a method of tapping power off of the battery from the device under test to power the testing circuit with a fixture that includes a magnet for the electrical connection. A method of developing experimental circuits is discussed in U.S. Pat. No. 4,384,752 “Hook-up wires with magnetic connectors” where a post and socket combination are required to make the electrical connections.
Finally a number of patents cover aligning a battery or holding the battery or device in place while it is being charged but do not contact the battery terminals themselves. Examples of this include U.S. Pat. No. 6,007,363 “Magnetically Latchable Device for Electrically Coupling a Power Source to a Circuit” and U.S. Pat. No. 7,026,789 “Charging System for Electronic Devices” where in both cases a battery is mounted on the battery or in the cradle where the battery will be laid into for charging to assist in holding the battery in place or aligning it properly. In these cases the battery also acts to trigger a sensor that it is present.
What is lacking in all of the previously discussed patents and prior art is the ability to magnetically connect to a battery to facilitate charging it, and most especially making a universal lead that can be quickly attached and detached to a variety of batteries or charging sources for the purposes of giving or taking a charge to or from the battery without recourse to special connector pairs and custom fixtures. Furthermore none of the above mentioned inventions discuss using such a magnetically attachable lead for the purposes of charging small batteries for portable devices, nor do they teach adding such a feature to a portable device to enable it to extract a charge from an external battery.